Question: Express this number in scientific notation. $\text{9 ten thousandths}$
$\text{9 ten thousandths}$ can be written as $0.0009$ in standard form. Count the zeroes to the right of the decimal point before the leading ${9}$ : there are $3$ zeroes. If you count the leading digit ${9}$, there are ${4}$ digits to the right of the decimal point. So: $\text{9 ten thousandths}= {9}.0 \times 10^{{-4}}$